Two healthy individuals have a healthy son. His

physical, motor, psychological, and social development fully corresponded to

his age. Now at the age of two, the patient is admitted for a suspected

fracture of the right tibia. The injury is negative and the mechanism of

fracture is unknown. In addition, he was already hospitalized once 5 months ago

for a left radius fracture. The mechanism of fracture was not identified here

either. Physical examination reveals limited mobility of the right lower

extremity, soreness in the lower tibia and gluteal region and a relatively

greater amount of bruising on the body overall. Slightly bluish sclerae are

noticeable. X-ray confirms the diagnosis of a fracture of the right tibia.

Basic laboratory findings (blood count and biochemistry) are normal. Genetic

testing shows that the disease is caused by a mutation and defect in collagen

formation associated with, among other things, increased bone fragility. This

is the disease